Confidence in Valentine's Day snowfall waning

9:30 p.m. UPDATE: Forecasters are maintaining decent snow chances for Carroll County and along the Mason-Dixon Line in Baltimore and Harford counties, but for most of the Baltimore area, Wednesday night's system is expected to bring another dusting of snow.

About 36 hours ahead of potential snowfall, forecasters were calling for at least an inch or two and possibly 4 inches of accumulation overnight Wednesday, according to the National Weather Service. As time passed Tuesday, though, confidence in that prediction was waning.

The weather service's Baltimore/Washington forecast office's forecast maps call for 1-2 inches across Baltimore, including southern Baltimore County and Howard County, with 2-4 inches in Carroll, northern Baltimore and Harford counties. South of Baltimore, an inch or less was expected. Those predictions were holding steady as of early Tuesday afternoon.

The forecasters expect rain early, turning to a wintry mix and then snow after about 9 p.m., tapering off by early Thursday morning. The heaviest precipitation could come after the air chills enough to support snow, according to the forecast discussion from early Tuesday morning:

"WARM NEAR SURFACE AIR MAY INITIALLY CUT DOWN ON SNOWFALL DURING THE DAYTIME ON WEDNESDAY...AND IT MAY TAKE UNTIL EVENING FOR AREAS /PARTICULARLY ACROSS THE NORTH AND WEST CWA/ TO CHANGEOVER TO SNOW. THIS WOULD HOWEVER COINCIDE WITH THE TIME WHERE THE BEST QPF MAY BE AVAILABLE AND WHERE A BAND OF AT LEAST MODERATE SNOWFALL MAY DEVELOP."

Some questioned the forecast, though, because of the presence of a lot of warm air. Temperatures reached the low- to mid-50s around the Baltimore area Tuesday and were expected to reach the mid- to upper-40s Wednesday and Thursday.

"It's probably going to be rain with a wet snow mix," said Andy Woodcock, a weather service meteorologist.

The Hydrometeorological Prediction Center in College Park had expected strong chances of as much as 4 inches of snow, as of forecasts from early Tuesday. But they were later revised to show just a 30-40 percent chance of an inch of snow.

Historic flooding and the coldest temperatures in decades made weather headlines in Baltimore in 2014. Rainfall records were set in April and August, and after a frigid winter, the summer was comfortable and fall cool. The year is expected to be the coolest and wettest here in years.